Extreme head morphology in Plastotephritinae (Diptera, Platystomatidae), with a proposition of classification of head structures in acalyptrate Diptera.

Modification of the head capsule in flies is known from several families of Diptera. In nearly all instances the accompanying agonistic behaviour suggests sexual selection for increased morphological change. This paper examines and explores the variety of head modifications found in the Plastotephritinae (Diptera, Platystomatidae) and, in the absence of biological observations regarding sexual behaviour and oviposition, suggests that similar agonistic, territorial behaviour and sexual selection is likely in Plastotephritinae. In addition, a system of classification of head modifications is proposed to aid future discussion and later (possibly phylogenetic) analysis, listing 9 (+ 1 intermediate) categories of head modification in Plastotephritinae and 4 further categories in other dipterous families